1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<html> 3<head> 4<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 5<title>Macro BOOST_PROTO_AUTO</title> 6<link rel="stylesheet" href="../../doc/src/boostbook.css" type="text/css"> 7<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 8<link rel="home" href="index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> 9<link rel="up" href="proto/reference.html#header.boost.proto.proto_typeof_hpp" title="Header <boost/proto/proto_typeof.hpp>"> 10<link rel="prev" href="BOOST_PROTO__1_3_33_5_35_5.html" title="Macro BOOST_PROTO_MAX_FUNCTION_CALL_ARITY"> 11<link rel="next" href="BOOST_PROTO_REPEAT.html" title="Macro BOOST_PROTO_REPEAT"> 12</head> 13<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 14<table cellpadding="2" width="100%"><tr> 15<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../boost.png"></td> 16<td align="center"><a href="../../index.html">Home</a></td> 17<td align="center"><a href="../../libs/libraries.htm">Libraries</a></td> 18<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 19<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 20<td align="center"><a href="../../more/index.htm">More</a></td> 21</tr></table> 22<hr> 23<div class="spirit-nav"> 24<a accesskey="p" href="BOOST_PROTO__1_3_33_5_35_5.html"><img src="../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="proto/reference.html#header.boost.proto.proto_typeof_hpp"><img src="../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="index.html"><img src="../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="BOOST_PROTO_REPEAT.html"><img src="../../doc/src/images/next.png" alt="Next"></a> 25</div> 26<div class="refentry"> 27<a name="BOOST_PROTO_AUTO"></a><div class="titlepage"></div> 28<div class="refnamediv"> 29<h2><span class="refentrytitle">Macro BOOST_PROTO_AUTO</span></h2> 30<p>BOOST_PROTO_AUTO — For defining a local variable that stores a Proto expression template, 31 deep-copying the expression so there are no dangling references.</p> 32</div> 33<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> 34<div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: <<a class="link" href="proto/reference.html#header.boost.proto.proto_typeof_hpp" title="Header <boost/proto/proto_typeof.hpp>">boost/proto/proto_typeof.hpp</a>> 35 36</span>BOOST_PROTO_AUTO(Var, Expr)</pre></div> 37<div class="refsect1"> 38<a name="id-1.3.33.5.38.4.4"></a><h2>Description</h2> 39<p> 40 To define a local variable <code class="computeroutput">ex</code> that stores the expression 41 <code class="computeroutput"><a class="link" href="boost/proto/lit.html" title="Function lit">proto::lit</a>(1) + 2</code>, 42 do the following:</p> 43<pre class="programlisting"><span class="identifier">BOOST_PROTO_AUTO</span><span class="special">(</span> <span class="identifier">ex</span><span class="special">,</span> <a class="link" href="boost/proto/lit.html" title="Function lit">proto::lit</a><span class="special">(</span><span class="number">1</span><span class="special">)</span> <span class="special">+</span> <span class="number">2</span> <span class="special">)</span><span class="special">;</span></pre> 44<p>. 45 The above is equivalent to the following: 46 </p> 47<pre class="programlisting"><span class="identifier">BOOST_AUTO</span><span class="special">(</span> <span class="identifier">ex</span><span class="special">,</span> <a class="link" href="boost/proto/deep_copy.html" title="Function template deep_copy">proto::deep_copy</a><span class="special">(</span> <a class="link" href="boost/proto/lit.html" title="Function lit">proto::lit</a><span class="special">(</span><span class="number">1</span><span class="special">)</span> <span class="special">+</span> <span class="number">2</span> <span class="special">)</span> <span class="special">)</span><span class="special">;</span></pre> 48<p> 49 </p> 50</div> 51</div> 52<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 53<td align="left"></td> 54<td align="right"><div class="copyright-footer">Copyright © 2008 Eric Niebler<p> 55 Distributed under the Boost Software License, Version 1.0. (See accompanying 56 file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) 57 </p> 58</div></td> 59</tr></table> 60<hr> 61<div class="spirit-nav"> 62<a accesskey="p" href="BOOST_PROTO__1_3_33_5_35_5.html"><img src="../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="proto/reference.html#header.boost.proto.proto_typeof_hpp"><img src="../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="index.html"><img src="../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="BOOST_PROTO_REPEAT.html"><img src="../../doc/src/images/next.png" alt="Next"></a> 63</div> 64</body> 65</html> 66
